Thursday, July 14, 2011

How to turn Lead into Gold - Alchemy 101

Before Science there was alchemy. Alchemy was a mix of crafts between science and mysticism and is probably the foundations of Chemistry.

The highest aim of alchemy was to turn base metal into gold by using transmutation. The meaning of transmute is to change from one form or substance into another; to transform or convert.

Lead was the most common base metal used but the goal of transmutation was not achieved until 1972.

To convert lead into gold requires a physical process rather than a chemical one. Lead has an atomic number 82 and gold has the atomic number 79. The atomic numbers are defined as elements by the number of protons they possess.

Changing the element requires changing the atomic (proton) number. In a circular particle accelerator, magnetic fields accelerate particles moving in circular paths. The accelerated particle impacts a target material, potentially knocking free protons or neutrons and making a new element or isotope. Nuclear reactors also may used for creating elements, although the conditions are less controlled.

Nature creates new elements by adding protons and neutrons to hydrogen atoms. This process occurs naturally within the nuclear reactions of stars. The process is called nucleosynthesis and creates increasingly heavier elements.

Elements heavier than iron are formed in the stellar explosion of a supernova. In a supernova gold can only be made into lead. Because lead is stable, forcing it to release three protons requires a vast input of energy, such that the cost of transmuting it greatly surpasses the value of the resulting gold.

However it is practical to get gold from lead ore.

The minerals galena, cerussit and anglesite often contain zinc, gold, silver, and other metals. Once the lead ore has been pulverized, chemical techniques are sufficient to separate the gold from the lead.